1. Field of Invention
The present invention relates to an air conditioner comprising an absorption chiller, and more particularly to an air conditioner comprising an absorption chiller of heat transfer medium drive type.
2. Related Art
In the air conditioner comprising the absorption chiller of heat transfer medium drive type that is driven by a heat transfer medium for driving which is heated, the cooling is performed by supplying a refrigerant cooled by activation of the absorption chiller to an indoor unit. On one hand, at the time of heating, the absorption chiller is driven by the use of exhaust heat source such as a hot water (entering a heat source from outside) to heat the heat transfer medium for heating that is supplied to the indoor unit, or a heat exchanger for heating, provided separately from the absorption chiller, is employed to heat the heat transfer medium for heating that is supplied to the indoor unit owing to heating of the heat transfer medium for driving.
Generally, there is a demand for improving the energy saving of the air conditioner. For this demand, the present inventors have contemplated that the energy saving of the air conditioner can be improved by utilizing effectively the heat energy of heat transfer medium in a heating operation of the air conditioner, and further suppressing the consumption of energy associated with the activation of the heat exchanger for heating or the absorption chiller. That is, the present inventors have contemplated that a heat transfer medium obtained from an exhaust heat source is supplied directly to the indoor unit to perform heating, whereby it is unnecessary to provide the heat exchanger for heating, and the activation of the absorption chiller or the units involving the operation of the absorption chiller is stopped when heating, whereby the energy consumption associated with the activation of the heat exchanger for heating or the absorption chiller is suppressed to improve the energy saving.
However, in the case where the heat transfer medium that is heated is supplied directly to the indoor unit, if the blow-off temperature of hot air from the indoor unit gets too high at the time of heating, due to the temperatures of the heat transfer medium, the temperature distribution in the room is difficult to become uniform, resulting in poor amenity in some cases. Also, if the temperature of heat transfer medium exceeds the heat resisting temperatures of the indoor unit or the control valve, there are some instances that the operation of the air conditioner may be hindered. Therefore, it is required that the temperature of heat transfer medium falls below the heat resisting temperatures of the system of units, and further the temperature is adjusted so that the temperature distribution within the room is likely to be uniform. On the other hand, when a refrigerant supplied to the indoor unit is cooled by the absorption chiller at the time of cooling, there are some instance that the absorption chiller can be never or less efficiently driven at the temperatures required for the time of heating. Accordingly, it is required that the temperature of heat transfer medium supplied to the absorption chiller at the time of cooling may be higher than at the time of heating. In this way, because the temperatures of heat transfer medium are different depending on whether the cooling or heating, there is the problem with the conventional air conditioner comprising the absorption chiller of heat transfer medium drive type that simply changing the pipes may result in the poor amenity within the room, the impeded operation of the air conditioner, or the lower cooling or heating efficiency, depending on the temperature of heat transfer medium, when heating.
It is an object of the present invention to improve the energy saving of an air conditioner.
An air conditioner of the present invention comprises heat transfer medium temperature adjusting means for adjusting the temperature of a heat transfer medium, an absorption chiller having as a heat source the heat transfer medium supplied from the heat transfer medium temperature adjusting means via a heat transfer medium line through which the heat transfer medium passes, a valve provided in the heat transfer medium line, a by-pass line branching off from the valve, and an indoor unit supplied with a refrigerant from the absorption chiller or the heat transfer medium from the heat transfer medium temperature adjusting means via the by-pass line.
Further, the heat transfer medium temperature adjusting means stops the heating of heat transfer medium at the highest temperature in a first temperature range, and starts the heating of heat transfer medium at the lowest temperature in the first temperature range, when the heat transfer medium passes through the absorption chiller, or stops the heating of heat transfer medium at the highest temperature in a second temperature range that is lower than the first temperature range, and starts the heating of heat transfer medium at the lowest temperature in the second temperature range when the heat transfer medium passes through the by-pass line.
Also, the heat transfer medium temperature adjusting means comprises an exhaust heat recovery unit for recovering an exhaust heat from an exhaust heat source into the heat transfer medium, a temperature sensor for sensing the temperature of heat transfer medium, and a control unit for controlling at least the exhaust heat recovery unit and the temperature sensor. Further, when the heat transfer medium passes through the absorption chiller, the control unit stops the exhaust heat recovery unit to recover the exhaust heat into the heat transfer medium, if the temperature sensor senses the highest temperature in a first temperature range, and starts the exhaust heat recovery unit to recover the exhaust heat into the heat transfer medium, if the temperature sensor senses the lowest temperature in the first temperature range, or when the heat transfer medium passes through the by-pass line, the control unit stops the exhaust heat recovery unit to recover the exhaust heat into the heat transfer medium, if the temperature sensor senses the highest temperature in a second temperature range that is lower than the first temperature range, and starts the exhaust heat recovery unit to recover the exhaust heat into the heat transfer medium, if the temperature sensor senses the lowest temperature in the second temperature range.
With such a constitution, at the time of heating, the valve is switched to allow the heat transfer medium to pass through the by-pass line, so that the heat transfer medium is supplied from the heat transfer medium temperature adjusting means via the by-pass line to the indoor unit. Hence, the heating operation can be performed by directly supplying the heat transfer medium to the indoor unit. In other words, in the heating operation, the activation of the absorption chiller or the devices involving the operation of the absorption chiller can be stopped, thereby reducing the consumption of energy used in the operation of the air conditioner. And the heat transfer medium temperature adjusting means can adjust the temperature of heat transfer medium to be higher when the heat transfer medium passes through the absorption chiller than when the heat transfer medium passes through the by-pass line. That is, since the temperature of heat transfer medium is controlled to be higher at the time of cooling than at the time of heating, it is unlikely that the poor amenity within the room at the time of heating, the impeded operation of the air conditioner, or the lower cooling or heating efficiency may occur. Accordingly, the air conditioner can be improved in the energy saving.
By the way, there are some instances that the temperature of exhaust heat from the exhaust heat source is too low to enable the heat transfer medium to effect the cooling or heating operation at full efficiency. In such instances, the conventional air conditioner stops the heat exchange from the exhaust heat source into the heat transfer source, and employs an auxiliary heater to heat the transfer medium. However, in this conventional air conditioner, the energy saving can not be fully attained because the heat from the exhaust heat source can not be effectively utilized.
On the other hand, an air conditioner of the invention comprises heat transfer medium temperature adjusting means having an auxiliary heater and a control unit for controlling the operation of this auxiliary heater. Further, when the heat transfer medium passes through the absorption chiller, the control unit stops the auxiliary heater to heat the heat transfer medium, if the temperature sensor senses the highest temperature in a third temperature range that is lower than the highest temperature in the first temperature range, and starts the auxiliary heater to heat the heat transfer medium at the lowest temperature in the third temperature range, if the temperature sensor senses the lowest temperature in the first temperature range, or when the heat transfer medium passes through the by-pass line, the control unit stops the auxiliary heater to heat the heat transfer medium, if the temperature sensor senses the highest temperature in a fourth temperature range that is lower than the highest temperature in the second temperature range, and starts the auxiliary heater to heat the heat transfer medium, if the temperature sensor senses the lowest temperature in the fourth temperature range.
With such a constitution, the auxiliary heater heats the heat transfer medium in a state where the exhaust heat from the exhaust heat source is recovered into the heat transfer medium, and stops the heating of heat transfer medium at a temperature below the temperature range of the exhaust heat recovery that is started or stopped. Therefore, the heat transfer medium recovers the exhaust heat except when the abnormally high temperature condition occurs to stop the exhaust heat recovery, and the auxiliary heater heats the heat transfer medium to supplement for insufficient heat with the exhaust heat recovery. Accordingly, in the case of employing the auxiliary heater, the exhaust heat obtained from the exhaust heat source can be effectively utilized by suppressing the energy consumption of the auxiliary heater as much as possible, whereby the energy saving of the air conditioner can be improved.
Also, if the temperature sensor and the control unit are employed to detect overheating of heat transfer medium, one temperature sensor can be utilized for both the control of the temperature of heat transfer medium and the detection of abnormal overheat, whereby there is the advantage that the number of temperature sensors can be reduced.